ORIGIN OF THE INVENTION
The invention described herein was made in the performance of work under a NASA contract, and is subject to the provisions of Public Law 96-517 (35 USC 202) in which the Contractor has elected not to retain title.
1. Technical Field
The invention relates to mobile robots for responding to hazardous materials emergencies where humans cannot go, and particularly to a light weight and economical robot of this type having little or no on-board robot computing ability.
2. Background Art
Hazardous materials emergencies require the penetration of buildings or other structures, which presents several problems. First, before deciding whether to open a door in such a structure, it is desireable to ascertain the nature of the environment behind the door. Secondly, opening the door may require the use of a key and/or the operation of a door latch and holding the door open against a self-closing mechanism. Use of a robot in penetrating such structures would avoid the risks in having humans do so. Such a robot would have to be self-powered, self-contained and small enough to fit into most passageways. However, a robot which can perform the perfectly linear motion required to insert a key into a door lock must have a powerful robot computing system consisting of either (a) a large box housing off-the-shelf integrated circuits on circuit boards or (b) a small but expensive box containing custom integrated circuits. Thus, it would appear that either the robot's compactness is compromised or else the cost of the robot is significantly increased. Also, a remote operator controlling the robot's movement of the key via a two-dimensional video monitor would be hampered because almost all humans are accustomed to inserting keys into door locks with a perspective view of the key and lock (as opposed to a straight-on or frontal view afforded by an arm-mounted or torso-mounted camera on the robot).
A related problem in ascertaining the nature of the environment behind a door to be opened is that a sensor (such as a chemical sensor) held at the end of the robot's arm must be positioned by the robot next to the space between the door and the door jamb. An operator viewing a video monitor while attempting to manually control the robot to perform such a task would be unable to gauge the robot arm's distance and speed relative to the door jamb, without the of a proximity sensor. Unfortunately, a proximity sensor must be interfaced to additional processing electronics and, in some cases, to the robot's on-board computer in order to acquire, transmit and display the speed or distance measurement to the operator. Hence, the electronic integration of a conventional proximity sensor has a significant impact upon various other components of the overall system.
Another problem in ascertaining the nature of the environment behind a door to be opened is that it is not desirable to hold the sensor (e.g., the chemical sensor) at the end of the robot arm, since it might be broken by accidental impact with the door or door jamb due to the operator's inability to judge the speed or range of the arm relative to the door jamb. Thus, the arm might hold in its hand or gripper the open end of a flexible hose line whose other end is connected to the input of the chemical sensor mounted at a safer location on the robot. The problem is that as the gripper rotates with the arm to perform other tasks, the hose will eventually twist too far and either jam the arm or break.
Operating a robot is difficult for the uninitiated, because the operator manually controls joint motion in such robots and must therefore mentally predict the joint motion required to effect the desired hand or gripper motion. Moreover, the operator must know which control knob (or "joystick") controls a particular one of the several joints of the robot. Depending upon the immediate robot arm configuration and the desired hand motion, there can be an inverse relationship between the direction of joint motion and the direction of the hand motion, slowing or preventing appropriate operator action. Thus, the concept of an economical and unsophisticated hazardous materials emergency response robot of the type which every municipality could afford as standard fire station equipment and which could be readily and reliably operated in an emergency with a modicum of prior training has not seemed practical in view of the foregoing.
Various techniques related to the foregoing are known in the art. For example, a remote control robot for hazardous environments is disclosed in U.S. Pat. No. 4,652,204, but is not truly a self-contained mobile robot. U.S. Pat. No. 5,031,304 discloses compliant tools for use by a robot. U.S. Pat. Nos. 4,800,802 and 4,290,203 disclose various compliant tools for general use. U.S. Pat. Nos. 4,819,184 and 4,676,713 disclose, respectively, joysticks and rocker switch panels for robots. U.S. Pat. Nos. 4,615,615 and 4,843,565 disclose laser range finders.